Stylus Antenna Layout for Metal Tube and Sliding Cap Interference
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Solution Overview
Problem
It is challenging to design wireless circuitry for compact devices like computer styluses without compromising antenna performance due to the presence of conductive structures.
Innovation Solution
The computer stylus incorporates a printed circuit board with an antenna resonating element aligned with a window in the metal tube, and a movable cap with a metal hook that is grounded to prevent interference with the antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conductive structures are included in the stylus for mechanical support and functionality, then structural strength and mechanical support are improved, but antenna performance deteriorates due to interference from conductive materials
Solution Approach 1:
The metal tube is segmented by introducing a window that divides the conductive structure into separate regions. This segmentation allows the antenna resonating element to be positioned in a non-conductive region, reducing interference while maintaining the overall structural strength of the metal tube.
Solution Approach 2:
A window is extracted or removed from the metal tube to create a non-conductive region. This extraction eliminates the harmful conductive material from the antenna region, allowing the antenna to function properly without interference from the metal tube's conductive properties.
2Strength
If the cap is made conductive for mechanical coupling, then mechanical strength and coupling are improved, but antenna performance worsens due to interference from the conductive cap
Solution Approach 1:
The conductive cap is segmented by introducing a break or non-conductive region that allows the antenna resonating element to pass through or be positioned near the cap without interference. This segmentation maintains the mechanical coupling function while eliminating electromagnetic interference.
Solution Approach 2:
A non-conductive intermediary element is introduced between the conductive cap and the antenna resonating element. This intermediary allows the conductive cap to maintain its mechanical coupling function while preventing it from interfering with the antenna's electromagnetic field.
3Volume of moving object
If the stylus is designed in compact form for portability, then portability and ease of use are improved, but antenna performance deteriorates due to limited space for antenna configuration
Solution Approach 1:
The antenna resonating element is configured to operate in a specific spatial dimension or orientation that utilizes the limited space within the compact stylus. By optimizing the antenna's dimensional configuration, sufficient radiation pattern is achieved despite the small form factor.
Solution Approach 2:
The antenna resonating element is positioned in a specific local region of the stylus where the radiation pattern can be optimized. This local optimization allows the antenna to achieve desired performance in specific directions while maintaining the overall compact design of the stylus.
Data Source
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AI summary
A computer stylus (10) may have a shaft (16) with a metal tube (70) and a cap (18) slidable between open and closed positions. A connector port (84) may be exposed in the open position and hidden in the closed position. An antenna element (40) may be formed from conductive traces on a printed circuit board (76) in the shaft (16) and aligned with a window (88) in the metal tube (70). The cap (18) may include a metal hook (108) extending from a conductive wall (96) into the shaft (16). The hook (108) may overlap the antenna element (40) in the closed position. The shaft (16) may include a dielectric bumper (112) in an opening of the hook (108). The hook (108) and wall may slide relative to the shaft (16) along the dielectric bumper (112). The cap (18) may include a metal sleeve (86) around the port (84). The cap (18) may include a conductive bumper (100) on the wall. The conductive bumper (100) may contact the sleeve (86) when the cap (18) is in the closed position.